If you want to add subs with serious low end and super speed and transparancy, you should look at the wisdom audio sts subwoofer. I should disclose that I am a dealer and sell these. However, it is the best subwoofer I've ever heard. It is a pair of 15's in a regenerative transmission line enclosure. You can go to the wisdom aid owe site and read awhile paper on this. It is big. It is 101db sensitive. It goes down to a legitimate 15 to 20 and will move as much air as roughly 5 or 6 watch dogs or jl113's (which I also sell). It is unbeleivably fast and transparent. It is the sub I would use, if you want to add subs. There is no reason whatsoever to think that they need to be stereo subs. If you did this, you should run the maxxes full range and simply add the subs- I would try 30 to 50 hz as a crossover point. This will allow you to add more energy into the room where the maxxes are beginning to roll off ( due to room anomolies- no fault of the maxxes) and you have a good chance to linearize the bass response. Check it out- it's a beast, and the fastest, quickest bass I know of.
